I noticed today that my Swingle rootstock have a nice flush going on.

http://img683.imageshack.us/img683/5018/swingleflush.jpg

If I remember correctly, this means the bark is slipping, is this right?

Yes, the bark should be slipping-ready for grafting! Good Luck.

Skeeter help me out, I have been grafting for years , whip and clef starting in October through February. usually with good results , I have never thought about bark slipping for grafting, what am I missing. I do want to do some budding in the future and understand the reason for the bark to slip. but I just might be missing some detail. thanks

Bark slipping is when you make a cut into the cambien( the outer skin which is like a shirt over the bark) and can easily remove or peel up. In order to be successful in t budding or bark grafting you need the bark slipping , unlike cleft and whip you don't need bark slipping.
Edit--- you are doing your grafts under the cambium when you are t budding or bark grafting so you need active flow of nutrient ie. Bark slipping helps this process because you know that there is a flow.

Which months are right to grafting and budding?
In which months is bark slipping or in which months bark isn't slipping?
When can I start grafting?

bark is slipping here in south texas starting in febraury but can change in different areas. When you see your citrus with a good amount of flush on it you are ready to be grafting. Make sure temps are above 50 degree low and not over 95, i have seen anything over 95 my grafts seem to die.

Jimi I whip graft and cleft graft citrus starting in October and continue through February when they are growing at the slowest rate. The trees that I graft are 3 gallon pot size in a greenhouse so they are growing all the time. I graft in the winter because it is cooler in GH and warmer than outside so it just works better for me.